then the seller went to weigh out the sugar for me, while I took the coins from my pocket and handed them to him. Here, the contract was concluded over something owed as a liability in exchange for something owed as a liability.
His statement, “or a lawful benefit,” means an exchange of property for a lawful benefit. An example is a right of passage through a house. A man owns a house, and he has a neighbor whose house lies between his own and the street. The other man says, “I would like to purchase from you a passage through your house to the street.” He replies, “Yes.” So he purchases from him the passage to the street for some dirhams. This is called an exchange of property for a benefit.
The neighbor who purchased this benefit from his neighbor has no right except to pass from his house through his neighbor’s house to the street. He may not dispose of this passage. Thus, if he says, “I will pave the passage through which I intend to reach the street,” the owner of the house has the right to prevent him and say, “It is not your property; you only have the right of passage.” The right of passage is the benefit: you have a right against me that I will not prevent you from making use of it, because you own the benefit. This, then, is an exchange of property for a benefit.
It is now clear that the subject matter of a contract is either tangible items or benefits. Tangible items are either specified or owed as a liability.
His statement, “a lawful benefit,” excludes an unlawful benefit. For example, if someone were to purchase the use of a musical instrument, saying, “Sell me the use of this instrument,” and then says, “I will purchase it from you solely to use it for fifty riyals,” and the other replies, “I have sold it to you,” this is not permissible, because the benefit in this case is prohibited. Every contract concerning something prohibited is invalid, due to the statement of the Messenger of Allah, peace and blessings be upon him: “Whoever performs an act that is not in accordance with this matter of ours, it is rejected.” (1)